Since the 1990s, the links among the global economy, trade, and finance have been significantly strengthened, as have the effects of financial cross-market risks. When one sub-market of the financial market experiences a shock, the other sub-market will also fluctuate as a result of the risk conduction effect. In extreme cases, systemic financial risks could even erupt. Both the 2008 financial crisis and the 2015 stock market crash had led to the spread of systemic risks in China’s financial markets, the Chinese government has put forward new goals and requirements for economic development, known as the “New Normal”. However, the COVID-19 epidemic in 2019 has not only affected the normal life of the Chinese people but also the development of the production and investment of Chinese enterprises. Against the background of the epidemic, China’s financial market has entered a unique “New Normal”. In the context of the “New Normal” of China’s financial market, many scholars have studied some characteristics of China’s financial markets and financial institutions by using various techniques and methods and obtained some meaningful conclusions. For example, Ribeiro GT considered that the prediction of stock price volatility was important for financial companies and investors to measure and manage market risk and support financial decision-making [
1]. Therefore, this paper is meant to study the impact of COVID-19 on financial enterprises in China from 2016 to 2021, hoping to provide some suggestions for the stable growth of such markets.
With the development of network science, more and more researchers used the properties of complex networks to study the contagion risk of financial markets. For example, the variant of artificial neural network has been proposed, such as Echo state network (ESN), which based on the reservoir computing paradigm, have been proposed to improve time series prediction. Yang conducted an empirical study about U.S. Treasury bonds, global stock indices and commodities by identifying volatility spillover networks and found that the U.S. stock market was the center of the international volatility spillover network, and its volatility spillover effect has intensified since 2008 [
2]. Zhang used complex network theory and GARCH-BEKK model to study the causes of financial risks and the spatial spillover effects of G20 stock market volatility [
3], the dynamic volatility spill-over effect between stock indexes and commodity futures markets was empirically examined by Sang using the theory. It was determined that the index and commodity futures had a positive association [
4]. Xie explained the evolution of extreme risk spillovers in China’s financial sub-market by using directed weighted complex networks. The empirical results show that although the energy secondary market continues to evolve over the five stages, it remains the main recipient of significant upside risk spillovers. After the financial crisis, there were a strong extreme risk spillover effect between the commodity and bond submarkets due to their increased ability to transmit extreme risk spillovers in the network [
5]. Hao constructed a risk contagion network in China’s financial markets and studied the changes of risk spillovers in the financial system in the five years before and after the outbreak of COVID-19 [
6]. Based on the idiosyncratic volatility spillover effects among the money market, capital market, commodity trading market, foreign exchange market, real estate market, and gold market, Gong constructed a complex information spillover network and investigated the characteristics of risk contagion within the financial system from the network perspective [
7]. In order to determine the risk center and development process of the crisis, Liu employed the spillover index and complex network methods to quantify the intensity and direction of risk spillovers in China’s financial market from a static and dynamic perspective [
8]. Based on historical data from China from January 1996 to December 2016, Zhao established a volatility spillover model of financial markets and demonstrated the cross-market volatility spillover impact [
9]. Based on the GARCH-BEKK model, Li built a volatility spillover network connecting several stock market locations in China and examined the risk contagion effect between these regions [
10]. Based on a regime switching skew-normal (RSSN) model, Luo investigated the linear and non-linear dependence structures of risk contagions between global crude oil futures markets and China’s agricultural futures markets, identifying the contagion channels under both stable and erratic oil market conditions [
11]. According to the authors’ findings by Feng, cross-shareholding networks were said to strengthen stock market linkages and led to risk contagion. Based on his research, cross ownership can reduce the impact of minor and sustained external shocks and volatility is highly sensitive to changes in network density [
12].
Furthermore, some scholars have studied the characteristics of financial institutions based on complex networks. For example, Huang first studied the return spillover effect among financial institutions. Then, the Granger causality in vector autoregressive (VAR) model is used to construct a core revenue network. Finally, he calculated the impact of the network centrality of financial institutions on measuring the scientific importance of financial institutions [
13]. Chuang investigated the potential effects of interconnectivity inside a securities firm on stock returns and suggested a financial network model to mimic the information transfer process of investors within a securities company [
14]. Ouyang used the directed network method to measure the systemic risk contagion effect of China’s banking industry, and the results showed that with the outbreak of the crisis, the correlation degree of the financial system was continuously enhanced, and the overall connectivity of the network was continuously enhanced until it reached the maximum level. However, systemic risk tends to lag behind the overall connectivity of the network [
15]. Utilizing data from 111 Chinese banks from 2013 to 2016, Chen concluded that the risk contagion faced by Chinese banks varied depending on the bank network structure and that raising capital levels helped banks be more resilient to credit and liquidity shocks [
16]. Fan used empirical Bayesian techniques to integrate the correlation between institutional stock returns, sentiment and marginal expectation gap, and concluded that excessive links among financial institutions would produce contagion effects and make financial shocks more severe [
17]. To the best of our knowledge, up to now, the introduction of DCC-GARCH model in complex networks to study risk contagion in financial markets has received little attention. Motivated by the above discussion, the main purpose of this paper is to discuss the changes of Chinese financial market before and after the COVID-19 from the perspective of risk contagion. In order to explore the dynamic correlation coefficients between China’s financial sub-markets, we first use the DCC-GARCH model. Next, we build complex networks, and the minimal spanning tree model is used to show the risk contagion path among Chinese financial sub-markets.